Protein klotho is a single-pass transmembrane protein and circulating humoral factor extensively investigated across preclinical models of renal physiology, cellular senescence, and neurobiology. PX1 Research provides high-purity, research-grade protein klotho verified via RP-HPLC and mass spectrometry for rigorous in vitro and laboratory experimental applications.
Protein klotho is a single-pass transmembrane protein and circulating humoral factor extensively investigated across preclinical models of renal physiology, cellular senescence, and neurobiology. PX1 Research provides high-purity, research-grade protein klotho verified via RP-HPLC and mass spectrometry for rigorous in vitro and laboratory experimental applications.
Protein klotho is a single-pass transmembrane protein and circulating humoral factor primarily expressed in the renal tubule epithelium, choroid plexus, and parathyroid glands. Functioning as a critical co-receptor for fibroblast growth factor 23 (FGF23) and an enzyme regulating oxidative stress pathways, protein klotho is widely studied in cellular senescence, calcium-phosphate homeostasis, and neuroprotective preclinical models.
Discovered originally as an anti-aging gene in murine models, the klotho gene encodes a protein that exists in two primary functional forms: a full-length transmembrane protein (approximately 130 kDa) and a shed, soluble protein (s-Klotho, approximately 110 kDa). The full-length membrane isoform functions predominantly in the kidney as an obligate co-receptor with FGF receptors (FGFR1c, FGFR3c, FGFR4) to mediate high-affinity binding of FGF23. Conversely, the soluble isoform is generated via proteolytic cleavage of the extracellular domain by membrane-bound metalloproteinases ADAM10 and ADAM17. Once shed into the systemic circulation, cerebrospinal fluid, and urine, soluble protein klotho acts as an endocrine or paracrine factor capable of modulating diverse signaling cascades independently of FGF23.
In vitro data demonstrate that the primary canonical pathway of protein klotho involves its obligate partnership with FGF receptors to control mineral homeostasis. In renal proximal and distal convoluted tubules, the Klotho-FGFR complex facilitates FGF23 signaling, leading to the downregulation of sodium-phosphate co-transporters (NaPi-2a and NaPi-2c) and suppression of 1α-hydroxylase expression. This signaling cascade serves as a principal regulator of serum phosphate and vitamin D synthesis in mammalian experimental systems.
Beyond mineral metabolism, non-canonical signaling mechanisms governed by soluble protein klotho have drawn intense interest in cell culture models. Soluble protein klotho exhibits endogenous sialidase activity, modifying the glycan chains of membrane channels such as TRPV5 and ROMK1 to regulate ion channel retention at the cell membrane. Furthermore, cell culture assays indicate that soluble protein klotho directly inhibits the Wnt/β-catenin signaling pathway by binding to secreted Wnt ligands, thereby suppressing cellular senescence cascades. In vitro investigations documented in the PX1 research library demonstrate that protein klotho also attenuates insulin and insulin-like growth factor-1 (IGF-1) signaling, enhancing intracellular resistance to oxidative stress via FOXO transcription factor activation.
In preclinical animal models and immortalized cell lines, protein klotho is evaluated across several distinct experimental domains. In renal disease models, loss of endogenous klotho expression is a hallmark of acute kidney injury (AKI) and chronic kidney disease (CKD). Exogenous administration of recombinant protein klotho in rodent models has been shown to reduce renal fibrosis, suppress epithelial-to-mesenchymal transition (EMT), and inhibit nuclear factor kappa B (NF-κB) driven inflammatory cytokine expression.
In neurobiological research, protein klotho expression within the choroid plexus and hippocampus declines markedly with experimental biological age. Preclinical mouse models overexpressing klotho demonstrate enhanced synaptic plasticity, elevated NMDA receptor subunit expression (specifically GluN2B), and improved cognitive task performance. In vitro neural cultures treated with research-grade protein klotho show decreased reactive oxygen species (ROS) accumulation and enhanced oligodendrocyte maturation, underscoring its relevance in neurodegenerative and demyelinating disease models.
When evaluating longevity and cellular longevity pathways in vitro, laboratory investigators frequently compare protein klotho against other targeted peptide sequences. While protein klotho functions as a high-molecular-weight co-receptor and circulating enzymatic factor modulating FGF23 and Wnt signals, smaller synthetic peptides act through alternative genomic or organellar mechanisms. For instance, epitalon is studied for its ability to induce telomerase activity and regulate pineal gland gene expression, whereas targeted senolytic constructs like FOXO4-DRI selectively disrupt p53-FOXO4 binding to trigger apoptosis in senescent cells.
Similarly, mitochondrial-derived peptides like MOTS-c regulate metabolic homeostasis and insulin sensitivity at the organelle level, and cell-permeable peptides like SS-31 target cardiolipin within the inner mitochondrial membrane to suppress electron transport chain ROS leakage. Researchers designing multi-target in vitro longevity screens often source these distinct modalities from our comprehensive catalog of research peptides to systematically map complementary protective cascades.
Because protein klotho assays depend on structural integrity, correct tertiary folding, and batch-to-batch consistency, rigorous quality control is paramount for reproducible lab data. PX1 Research manufactures all compounds in state-of-the-art, GMP-compliant USA facilities, ensuring complete lot traceability and strict adherence to ISO 17025 laboratory standards.
Every production lot of protein klotho undergoes analytical verification prior to release. Purity is characterized using Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC) to confirm peptide fidelity (≥98% purity standard), alongside Electrospray Ionization Mass Spectrometry (ESI-MS) to confirm precise molecular mass. Furthermore, because bacterial endotoxins interfere with cell culture assays and immune cell response studies, PX1 conducts chromogenic Limulus Amebocyte Lysate (LAL) testing on every lot to guarantee endotoxin levels remain strictly under 0.1 EU/mg. Orders are fulfilled directly from our CA and AZ distribution hubs with same-day shipping available Monday through Friday.
Protein klotho is supplied as a lyophilized, sterile powder to maintain structural stability during transit and long-term storage. For optimal reconstitution in laboratory settings, containers should be centrifuged briefly at low speed prior to opening to consolidate the lyophilized cake at the bottom of the vial.
Reconstitution should be performed using sterile, endotoxin-free water or phosphate-buffered saline (PBS, pH 7.4). If low-concentration working aliquots are prepared for long-term cell culture experiments, adding a carrier protein such as 0.1% Bovine Serum Albumin (BSA) is recommended to prevent non-specific adsorption to plastic microcentrifuge tubes. Reconstituted solutions should be aliquoted into single-use experimental volumes and stored at -80°C to avoid repeated freeze-thaw cycles, which degrade protein secondary and tertiary structures.
In cell culture experimental designs, soluble protein klotho is typically supplemented into culture media at concentrations ranging from 10 ng/mL to 500 ng/mL, depending on the targeted signaling event. For Wnt inhibition assays, pre-incubation of media containing recombinant Wnt ligands with protein klotho for 30–60 minutes prior to cell exposure yields consistent inhibition of TCF/LEF reporter activity.
Quantification of endogenous soluble Klotho in biological media or supernatants is typically performed via sandwich Enzyme-Linked Immunosorbent Assay (ELISA) or high-sensitivity Western Blotting using monoclonal antibodies directed against the KL1 or KL2 extracellular domains. For laboratories running high-throughput screening or continuous cell culture lines, establishing a wholesale laboratory account provides institutional pricing structure and lot-reserved material consistency across longitudinal studies.
All formulations of protein klotho and secondary research compounds available from PX1 Research, including tissue repair sequences such as BPC-157 or pituitary-axis secretagogues like GHRP-2, are strictly intended for laboratory in vitro and preclinical research applications. They are not intended for human or veterinary clinical use, diagnostic procedures, or therapeutic administration.
Institutional buyers can access complete lot-specific Certificates of Analysis (COAs) directly through our online portal, detailing HPLC chromatograms, mass spectra, and endotoxin assay reports for every fulfilled order.
What is protein klotho and what is its primary biological role?
Protein klotho is an enzymatic transmembrane and circulating protein primarily expressed in the kidneys and brain. It functions as an essential co-receptor for FGF23 in phosphate metabolism and operates independently as a circulating humoral factor that inhibits Wnt and IGF-1 signaling pathways.
What are the key differences between α-Klotho and β-Klotho isoforms?
α-Klotho is the classical form involved in renal phosphate clearance, aging models, and Wnt suppression. β-Klotho is a homologous transmembrane protein that acts as a co-receptor specifically for FGF19 and FGF21, regulating bile acid synthesis and energy metabolism in hepatic and adipose tissues.
How is protein klotho used in preclinical in vitro research?
In vitro, protein klotho is added to cell culture media to study mechanisms of cellular senescence, oxidative stress resistance, Wnt/β-catenin pathway regulation, renal tubule protection, and neuronal/synaptic development.
What purity specifications does PX1 Research guarantee for protein klotho?
PX1 Research guarantees a minimum purity of ≥98% as determined by Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC), with molecular identity confirmed by mass spectrometry (ESI-MS) and endotoxin levels tested below 0.1 EU/mg.
How should lyophilized protein klotho be reconstituted in the laboratory?
Lyophilized protein klotho should be reconstituting using sterile, endotoxin-free PBS or sterile water. For low-concentration working stocks, adding 0.1% carrier protein (such as HSA or BSA) prevents adsorption to container walls.
What are the recommended storage temperature parameters for protein klotho?
Lyophilized protein klotho should be stored at -20°C or -80°C upon receipt. Once reconstituted, stock solutions should be aliquoted and maintained at -80°C to prevent degradation caused by freeze-thaw cycles.
Is protein klotho available for institutional bulk or wholesale procurement?
Yes, PX1 Research offers institutional supply agreements, lot reservation, and bulk procurement options for university laboratories and research facilities through our wholesale portal.
How does protein klotho interact with the FGF23 receptor complex?
Protein klotho forms a physical complex with canonical FGF receptors (FGFR1c, FGFR3c, FGFR4), increasing their binding affinity for FGF23 by several orders of magnitude to initiate intracellular kinase cascades.
What analytical methods are included on the Certificate of Analysis (COA)?
Every PX1 COA includes RP-HPLC chromatograms for purity verification, ESI-MS mass spectrographs for sequence identity, and LAL chromogenic assay results for bacterial endotoxin quantification.
Can protein klotho be combined with other longevity research compounds in experimental assays?
Yes, investigators frequently evaluate protein klotho alongside other anti-aging research peptides like Epitalon, FOXO4-DRI, or MOTS-c to evaluate multi-pathway cellular responses in vitro.
All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.